Understanding Equine StranglesChristina L. Garloff, DVMEquine Veterinary Associates, Inc.
HistoryFirst reported in 1251Highly contagious Young horses most commonly affectedRecurrence at farm commonMost commonly diagnosed contagious disease worldwideCause Bacterial infection with Streptococcus equi subspecies equi (S. equi)Location Usually affects the upper airway and lymph nodes of the head & neck,but can be seen in other portions of the body
Clinical Signs Common: Fever (> 101.5°F) Anorexia, depression, difficulty swallowing Nasal discharge Enlarged submandibular lymph nodes Purulent nasal discharge Less common Enlarged retropharyngeal lymph nodes Guttural pouch infection-Empyema Enlarged lymph nodes on other portions of the head
Complications Most recover without complication Infection in other parts of the body Metastatic infection or Bastard Strangles Strangulation of airway Tracheostomy Immune mediated disease Purpura Hemorrhagica Muscle disease Decreased milk production in mares
Transmission Nasal/abscess discharge from infected horse Days to weeks Nasal discharge from asymptomatic carrier Months to years Contaminated environment Water-over 1 month, ground/bedding variable Contaminated equipment &/or handlers Buckets, feed tubs, grooming equipment, stall cleaning supplies, tack, clothing, otheranimals
Diagnosis Clinical signs highly suggestive Culture of discharge PCR nasal swab Start shedding a few days after fever onset Intermittent for several weeks 4-50% of horses on recurrent farms are carriers Months to years Blood titer-rise in levels when infected
Treatment Antibiotic therapy remains controversial Needed for complicated cases Anti-inflammatories for pain/fever Hot pack affected area +/- drawing agent (Ichthammol, etc.) Surgically lance when mature Soft feed if throat is sore Isolation from other horses!!
Outbreak Management Horse movement in and out of stable should stop Monitor temperatures twice daily Isolate at first sign of fever Contagious 1-2 days after fever begins
Outbreak Management Create three separate groups Clean horses with no exposure Separate area & separate caretakers & equipment Daily care should be first Exposed horses Infected horses
Outbreak Management Infected horses Use protective clothing Care for last Use dedicated equipment Thoroughly disinfect equipmentbetween horses Thoroughly disinfect hands andshoes between horses Disinfect water buckets daily Waste from infected horses shouldbe isolated & disposed of separately Rest exposed turn-outs/arenasminimum of 4 weeks Three consecutive negative PCRswabs (at least one week apart) foreach horse before returning togeneral population
Vaccination Does not guarantee disease prevention Intramuscular route High rate of vaccine reactions Approx 60% effective Intranasal route Current recommended vaccine Initial 2 doses, 2-3 weeks apart-protected 1 month aftersecond dose, annual booster Not recommended during an outbreak Recovered horses often develop immunity for 1 yearor more
Preventative Measures Require current health certificates for all new horses Obtain Strangles history/require negative PCR test before allowing on property Consider vaccination requirement before arrival Quarantine new horses for a minimum of 3 weeks before allowing in general population Monitor temp daily Each horse should have a dedicated water bucket that is disinfected regularly Minimize exposure to other horses/supplies at shows Pastured horses should be grouped by age & risk level